1. Field
The present application is directed to resettable circuit interrupting devices including without limitation ground fault circuit interrupters (GFCI's), arc fault circuit interrupters (AFCI's), immersion detection circuit interrupters (IDCI's), appliance leakage circuit interrupters (ALCI's), equipment leakage circuit interrupters (ELCI's), circuit breakers, contactors, latching relays and solenoid mechanisms. More particularly, the present application is directed to circuit interrupting devices that include a circuit interrupting portion that can break electrically conductive paths between a line side and a load side of the device and between a line side and a user load. Certain embodiments of the present application are directed to circuit interrupting devices including a reset lock out portion capable of preventing the device from resetting if the circuit interrupting portion is not functioning, if an open neutral condition exists or if the device is mis-wired. Certain embodiments of the present application are directed to methods of manufacturing circuit interrupting devices to be initially in a tripped condition. Certain embodiments of the present application are directed to methods of manufacturing circuit interrupting devices to be initially in a reset lock out condition.
2. Description of the Related Art
Many electrical wiring devices have a line side, which is connectable to an electrical power supply, and a load side, which is connectable to one or more loads and at least one conductive path between the line and load sides. Electrical connections to wires supplying electrical power or wires conducting electricity to the one or more loads are at line side and load side connections. The electrical wiring device industry has witnessed an increasing call for circuit breaking devices or systems which are designed to interrupt power to various loads, such as household appliances, consumer electrical products and branch circuits. In particular, electrical codes require electrical circuits in home bathrooms and kitchens to be equipped with ground fault circuit interrupters (GFCI), for example. Presently available GFCI devices, such as the device described in commonly owned U.S. Pat. No. 4,595,894, use an electrically activated trip mechanism to mechanically break an electrical connection between the line side and the load side. Such devices are resettable after they are tripped by, for example, the detection of a ground fault. In the device discussed in the '894 patent, the trip mechanism used to cause the mechanical breaking of the circuit (i.e., the conductive path between the line and load sides) includes a solenoid (or trip coil). A test button is used to test the trip mechanism and circuitry used to sense faults, and a reset button is used to reset the electrical connection between line and load sides.
However, instances may arise where an abnormal condition, caused by for example a lightning strike, occurs which may result not only in a surge of electricity at the device and a tripping of the device but also a disabling of the trip mechanism used to cause the mechanical breaking of the circuit. This may occur without the knowledge of the user. Under such circumstances an unknowing user, faced with a GFCI which has tripped, may press the reset button which, in turn, will cause the device with an inoperative trip mechanism to be reset without the ground fault protection available.
Further, an open neutral condition, which is defined in Underwriters Laboratories (UL) Standard PAG 943A, may exist with the electrical wires supplying electrical power to such GFCI devices. If an open neutral condition exists with the neutral wire on the line (versus load) side of the GFCI device, an instance may arise where a current path is created from the phase (or hot) wire supplying power to the GFCI device through the load side of the device and a person to ground. In the event that an open neutral condition exists, current GFCI devices, which have tripped, may be reset even though the open neutral condition may remain.
Commonly owned application Ser. No. 09/138,955, filed Aug. 24, 1998, now U.S. Pat. No. 6,040,967, which is incorporated herein in its entirety by reference, describes a family of resettable circuit interrupting devices capable of locking out the reset portion of the device if the circuit interrupting portion is non-operational or if an open neutral condition exists.
Some of the circuit interrupting devices described above have a user accessible load side connection in addition to the line and load side connections. The user accessible load side connection includes one or more connection points where a user can externally connect to electrical power supplied from the line side. The load side connection and user accessible load side connection are typically electrically connected together. An example of such a circuit interrupting device is a GFCI receptacle, where the line and load side connections are binding screws and the user accessible load side connection is the plug connection to an internal receptacle. As noted, such devices are connected to external wiring so that line wires are connected to the line side connection and load side wires are connected to the load side connection. However, instances may occur where the circuit interrupting device is improperly connected to the external wires so that the load wires are connected to the line side connection and the line wires are connected to the load connection. This is known as reverse wiring. In the event the circuit interrupting device is reverse wired, fault protection to the user accessible load connection may be eliminated, even if fault protection to the load side connection remains.
Furthermore, studies related to GFCI devices indicate that perhaps 10–20% or more of all GFCI devices installed were found to be inoperable by the user. However, after those devices were returned to the manufacturer, most were found to be operational. Accordingly, it has been suggested that the devices were reverse wired by the user (line-load side reversal). Furthermore, regulatory codes and industry standards codes such as those by Underwriters Laboratories (UL) may require that GFCI devices be manufactured with a warning label advising the user to correctly wire the line and load terminals of the device. However, even such warnings may not be adequate as suggested by the studies above. Furthermore, a reasonably foolproof mis-wiring prevention scheme may obviate the need for such a warning label.
Conventional GFCI devices may utilize a user load such as a face receptacle. Typically GFCIs are four terminal devices, two phase or AC leads for connection to AC electrical power and two LOAD leads for connection to downstream devices. If a conventional GFCI is properly wired, the GFCI provides ground fault protection for devices downstream and the incorporated receptacle. However, if a conventional GFCI is reverse wired, unprotected power is provided to the receptacle face at all times. For example, when a conventional GFCI is reverse wired, the face receptacle is “upstream” from the current imbalance sensor coil. Accordingly, if the conventional GFCI is in either the tripped or normal state, the face receptacle is provide unprotected power.
In spite of detailed instructions that come packaged with most GFCIs and identification of AC and LOAD terminals, GFCIs are sometimes mis-wired. One reason that this problem exists is that in new construction, both the input line and downstream cables appear identical when the installer is connecting a new ground fault circuit interrupter. This is especially a problem in new construction where there is no power available in order to test which cable is leading current into the device.
The problem may be compounded when it is considered that many typical duplex receptacle GFCIs have a test button that will trip and shut off the power when pushed to verify operations of internal functions in the GFCI. However, use of the test button does not indicate whether the built in duplex receptacle is protected. Typical users may not be aware of this. Users simply test the device after installation and verify that the unit trips upon pressing the test button by way of an audible click, for example. This gives the user a false sense that all is well. What is actually happening when the GFCI is reverse wired is that the GFCI disconnects power from and protects everything downstream, but does not protect the receptacle contacts of the GFCI itself. The device will trip depending on the condition of internal components and irrespective of how the GFCI was wired. It does not matter that the GFCI was reverse wired when it was tested.
Certain references described devices that attempt to warn the user of a reverse wiring condition. For example, one approach utilizes a GFCI with reverse line polarity lamp indicator to indicate proper installation of the GFCI. See, for example, U.S. Pat. No. 4,412,193 issued to Bienwald et al. on Oct. 25, 1983 and assigned to the owner of the present invention. However, a push button needs to be manually pressed in accordance with instructions in order to detect whether the GFCI is mis-wired.
In another example, U.S. Pat. No. 5,477,412 issued to Neiger et al. on Dec. 19, 1995 and owned by the assignee of the present invention, is directed to a ground fault circuit interrupter incorporating mis-wiring prevention circuitry. Mis-wiring sense circuitry automatically triggers the generation of visual and audible alarms in the event of mis-wiring conditions. The circuit employs an alarm inhibiting technique that incorporates sense circuitry connected to the AC terminals on one side of the internal GFCI switches or relays and alarm generation circuitry connected to the load terminal on the opposite side.
Commonly owned application Serial No. application Ser. No. 09/204,861, filed Dec. 3, 1998, which is incorporated herein in its entirety by reference, describes a device to test for reverse wiring and provide an indication of reverse wiring.